JPH07297357A - Circuit for protecting semiconductor integrated circuit from overheat - Google Patents

Abstract

PURPOSE:To obtain an overheat protecting circuit, which is not erroneously operated under the state, that the operating temperature of an IC is in the vicinity of the starting temperature of overheat protecting operation. CONSTITUTION:A circuit for protecting an IC from overheat has a temperature monitoring circuit 1 for detecting the temperature of the IC, a monitored-result outputting circuit 2 for outputting the detected result of the temperature monitoring circuit 1, a discriminating circuit 3, which transmits only the output in a certain specified time among the outputs of the monitored result outputting circuit 2 to a signal generating circuit 4, and the signal generating circuit 4, which receives the signal from the discriminating circuit 3 and extends the output. Therefore, the discriminating circuit 3 prevents the overheat protection caused by the malfunction of the circuits 1 and 2 by excluding the output of the monitored-result outputting circuit 2, which is shorter than the specified time. The signal generating circuit 4 can set the temperature of the IC at the temperature which is further lower than the starting temperature of the overheat proteting operation by fixing the output for the specified time even if the temperature at which the overheat protecting operation is released is obtained. Since the overheat protecting state does not appear by the erroneous operation, the stable overheat protecting operation is performed even if the ICs are in the overcrowded mounting state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for protecting a semiconductor integrated circuit from overheating.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing a structure of a conventional semiconductor integrated circuit (hereinafter also referred to as an IC) for protecting it from overheating. In FIG. 10, 101 is a temperature monitor circuit provided in the IC for detecting the temperature in the IC,
Reference numeral 102 denotes a comparison circuit that outputs a signal to stop the operation of the main circuit in the IC according to the output of the temperature monitor circuit 101,
103 is an output terminal of the comparison circuit 102.

The operation of the circuit for protecting the conventional IC shown in FIG. 10 from overheating will now be described with reference to FIG. FIG. 11 is a characteristic diagram showing the operation of the overheat protection circuit. Generally, the comparison circuit 1 of the circuit that protects the IC from overheating
02 has temperature hysteresis. This is because when the overheat protection circuit operates due to an increase in the temperature of the IC, the main circuit in the IC is cut off, power consumption is suppressed and the temperature of the IC decreases, but if the comparison circuit 102 does not have temperature hysteresis. Is a phenomenon in which the cutoff state is released immediately after the temperature drops to enter the power consumption state, the temperature of the IC rises and the overheat protection circuit operates again to enter the cutoff state, a so-called thermal oscillation state. This is because it may happen.

In FIG. 11, the horizontal axis represents the temperature change of the IC, and the vertical axis represents the operating state of the overheat protection circuit. Since the IC is normally used at a temperature T ₁ outside the hysteresis region shown by P ₁ in FIG. 11, even if the comparison circuit 102 in the overheat protection circuit malfunctions when the power supply is turned on and off, the cutoff is immediate. There is no problem because it will be canceled.

Further, in the shut-off operation by the temperature rise from the normal temperature, the state changes from P ₁ to P ₄ in FIG. 11 when the temperature rises from T ₁ to T ₄ , and the comparison circuit 102 operates. In the state P ₅ , the main circuit of the IC is cut off. Then, the temperature lowers to the state P _{8 of the} temperature E, and the interruption is released to the state P ₂ . However, when the radiation efficiency is reduced due to over-packing of the IC, the IC temperature rises, and the IC is used at a temperature T ₃ higher than the normal use temperature T ₁ . In this case, the operating condition of the overheat protection circuit is P ₃
It is in. Here, when the power supply is turned on or off, if the comparison circuit 102 in the overheat protection circuit malfunctions, the main circuit is cut off, but since the operating temperature is at T _3, it is once cut off. Then, the state P ₇ shifts to the state P ₇ , resulting in the continuation of the cutoff state.

[0006]

Since the conventional circuit for protecting the semiconductor integrated circuit from overheating is configured as described above, if the IC is used at a temperature within the temperature hysteresis region, it malfunctions due to powering on and off. When the above occurs, there is a problem that the cutoff state is not easily released.

The present invention has been made in order to solve the above problems, and an overheat protection circuit which does not fall into a cutoff state even when a power supply is turned on and off under a high temperature condition where heat radiation efficiency is lowered. Aim to get.

[0008]

A circuit for protecting a semiconductor integrated circuit according to a first invention from overheating is provided at a predetermined position of the semiconductor integrated circuit, and the temperature at the predetermined position of the semiconductor integrated circuit is used as a reference. The temperature detection means that detects whether or not the temperature exceeds the predetermined temperature and outputs the detection result, and the output of the temperature detection means that is continuously given for a predetermined time is limited to the output of the temperature detection means. And a signal output means for extending the output of the temperature detecting means for a predetermined period and outputting the signal.

A circuit for protecting a semiconductor integrated circuit according to a second aspect of the invention from overheating is the circuit for protecting the semiconductor integrated circuit according to the first aspect of the invention from overheating, wherein the signal output means has a predetermined output of the temperature detecting means. A discriminating means for discriminating whether or not the time is continuously given, and a period during which the output of the temperature detecting means continues after the discrimination by the discriminating means and after the end of the output according to the discrimination result of the discriminating means. And a signal generating means for generating and outputting a signal during the predetermined period.

A circuit for protecting a semiconductor integrated circuit according to a third invention from overheating is a circuit for protecting the semiconductor integrated circuit according to the second invention from overheating, wherein the signal generating means is connected to the outside of the semiconductor integrated circuit. The length of the predetermined period can be adjusted according to the capacity to be stored.

A circuit for protecting a semiconductor integrated circuit according to a fourth invention from overheating is the circuit for protecting the semiconductor integrated circuit according to the second invention from overheating, wherein the signal generating means is built in the semiconductor integrated circuit. The length of the predetermined period can be adjusted according to the capacity.

[0012]

The output of the signal output means in the first aspect of the present invention is such that when the temperature of the predetermined position of the semiconductor integrated circuit exceeds the reference temperature for a predetermined time continuously, at least after the judgment, the reference temperature is exceeded. And for a predetermined period after the temperature becomes lower than the reference temperature, the signal output means exits. By controlling the operation of the semiconductor integrated circuit according to the output of the signal output means, that is, by stopping the circuit operation of at least a part of the semiconductor integrated circuit only during the period when this output is being output, to reduce the heat generation amount, It is possible to protect the semiconductor integrated circuit from overheating.

For example, even when the operating temperature of the semiconductor integrated circuit is close to the predetermined temperature, when the temperature is lower than the predetermined temperature, the detection result of the temperature detecting means always outputs that the semiconductor integrated circuit is lower than the predetermined temperature. There is no case where the signal output means shifts to the operation stop state of the temperature hysteresis loop due to a malfunction as in the past and continues to maintain the stop state of the semiconductor integrated circuit.

The discriminating means in the second invention discriminates whether or not the output of the temperature detecting means is continuously applied for a predetermined time. Therefore, when the output is not continuously given for a predetermined time, the dead zone can be set for the output time so that it is not necessary to respond to the output of the temperature detecting means.

Further, the signal generating means, with respect to the output of the temperature detecting means which is continuously given for a predetermined time, a period during which the output of the temperature detecting means continues after the discrimination by the discriminating means and a predetermined period after the end of the output. Since the signal is generated and output during the whole period, the signal output means can continue to output the signal for a predetermined period after the temperature of the semiconductor integrated circuit becomes lower than or equal to the predetermined temperature.

Since the signal generating means in the third invention can adjust the length of the predetermined period according to the capacity connected to the outside of the semiconductor integrated circuit, the signal generation means of the semiconductor integrated circuit depends on the state and environment of the semiconductor integrated circuit. When the cooling rate is different, a predetermined period can be set according to the cooling rate to easily realize the overheat protection circuit corresponding to each semiconductor integrated circuit.

In the signal generating means in the fourth aspect of the invention, the length of the predetermined period can be adjusted according to the capacity built in the semiconductor integrated circuit, so that the semiconductor integrated circuit can be cooled depending on the state of the semiconductor integrated circuit and its mounting. When the speeds are different, it is possible to easily realize the overheat protection circuit according to the semiconductor integrated circuit by setting a predetermined period according to the cooling speed in advance, and the capacity is built in the semiconductor integrated circuit. It is easy to downsize.

[0018]

【Example】

<First Embodiment> A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a circuit (hereinafter, also referred to as an overheat protection circuit) for protecting a semiconductor integrated circuit from overheating according to a first embodiment of the present invention. In FIG. 1, 1
Is a temperature monitor circuit provided in the semiconductor integrated circuit for detecting whether or not the temperature of the semiconductor integrated circuit is higher than a predetermined temperature, and 2 is a monitor result output circuit for outputting according to the monitor result a of the temperature monitor circuit 1. 3 is a monitor result output circuit 2
Discriminating circuit 4 which discriminates whether or not the output b is output for a predetermined time and outputs an output c corresponding to the signal output for a predetermined time or longer. The discriminating circuit 4 extends the output c of the discriminating circuit 3 for a predetermined period and outputs it. It is a signal generation circuit.

Next, the operation of the overheat protection circuit will be described. FIG. 2 is a graph showing the output of each part of the overheat protection circuit shown in FIG. In FIG. 2, a is a temperature monitor circuit 1.
, B shows the output of the monitor result output circuit,
c shows the output of the discrimination circuit 3 and d shows the output of the signal generation circuit. In the temperature monitor circuit 1, the value of the output signal decreases as the temperature of the IC increases.

The output b of the monitor result output circuit 2 inverts the signal when the output a of the temperature monitor circuit 1 falls below the reference voltage indicating the reference temperature, and conversely falls below the reference temperature when the temperature falls. That is, the signal is restored when the output a of the temperature monitor circuit 1 exceeds the reference voltage. For example, the point at which the output b of the monitor result output circuit 2 is inverted and the point at which it is restored are points a and c and points b and d shown in FIG.

The discriminating circuit 3 transmits a signal in the output b of the monitor result output circuit 2, which is maintained in the inverted state for a certain period of time, to the signal generating circuit 4 in the subsequent stage. For example, the signal output by the monitor result output circuit 2 between points a and b in FIG. 2 does not appear in the output c because the determination circuit 3 determines that the signal is shorter than the predetermined time. On the other hand, in the case of the signal between points C and D, the discrimination circuit 3 determines that it is longer than the predetermined period C to E, and the discrimination circuit 3 starts signal output from the point E in FIG. That is, the determination circuit 3 transmits the signal of the monitor result output circuit 2 to the next stage only when the signal of the monitor result output circuit 2 is inverted for the predetermined period t _d or more.

The signal generation circuit 4 receives the signal from the discrimination circuit 3 and generates a signal d for stopping the operation of a necessary portion in the semiconductor integrated circuit and outputs it from the output terminal Y. Then, instead of applying temperature hysteresis, the output is fixed for a time between a certain time point d and a point to a certain time even if the temperature falls below the reference temperature, and then the output is restored.

Consider the operation based on the IC chip temperature in FIG. First, point C in FIG. 2 indicates that the semiconductor integrated circuit has the temperature T ₄ in FIG. Only when the temperature exceeds T ₄ is the discrimination circuit 3 activated, and the signal generation circuit 4 receives the output of the discrimination circuit 3 and outputs a signal for preventing overheating of the semiconductor integrated circuit. The signal generation circuit 4 has a temperature hysteresis that does not immediately re-invert even when the temperature of the IC chip falls and becomes lower than the temperature T ₄ and re-inverts as if the temperature becomes T ₃ or T ₂ lower than T _3. Act like this. However, in reality, the inversion state is maintained depending on time, and the inversion state is maintained over the set temperature C,
Since it occurs after the temperature starts to drop again, it does not always have temperature hysteresis as in the conventional example. Therefore, even if the power is turned on / off at the point B in FIG. 11, a malfunction such as the conventional example in which the circuit in the IC is erroneously kept stopped due to the temperature hysteresis is not seen.

FIG. 3 is a circuit diagram showing the structure of a circuit for protecting the semiconductor integrated circuit according to the first embodiment of the present invention from overheating. In the temperature monitor circuit 1, Vr is a DC voltage source that generates a predetermined DC voltage between the positive electrode and the negative electrode regardless of the temperature change of the IC, and R1 is one end connected to the positive electrode of the DC voltage source Vr. A resistor having the other end, Q1 is a resistor R
It is an NPN bipolar transistor having a base connected to the other end of 1, an emitter connected to the negative electrode of the DC voltage source Vr, and a collector to which a constant current is supplied.

In the monitor result output circuit 2, I1, I
2 is a constant current source for supplying a direct current maintained at a predetermined value from the power supply potential Vcc, Q1 is an NPN bipolar transistor shared with the temperature monitor circuit 1, Q2 is a collector of the constant current source I1 and the NPN bipolar transistor Q1. It is an NPN bipolar transistor having a connected base, an emitter connected to the negative electrode of a DC voltage source Vr, and a collector connected to a constant current source I2.

In the discrimination circuit 3, Vs is a direct current voltage source for generating a predetermined direct current voltage between the positive electrode and the negative electrode, R2
Is a resistor having one end connected to the positive electrode of the DC voltage source Vs and the other end, and R3 is a resistor having one end connected to the other end of the resistor R2 and the other end connected to the negative electrode of the DC voltage source Vr. , C1 is a capacitor having one end connected to the collector of the NPN bipolar transistor Q2 and the other end connected to the negative electrode of the constant voltage source Vr, and COM1 is a resistor R2.
Has an inverting input terminal connected to the other end of the capacitor C1 and a non-inverting input terminal connected to one end of the capacitor C1, and when the voltage of the non-inverting input terminal becomes higher than the voltage of the inverting input terminal, a high level (power supply potential Vcc ) Output comparator.

In the signal generation circuit 4, I3 and I4 are constant current sources for supplying a direct current maintained at a predetermined value from the power supply potential Vcc, and Q3 is connected to the output terminal of the comparator COM1 and the constant current source I3. P having an emitter and one collector connected to the base of the NPN bipolar transistor Q1, and a base and another collector connected to each other
NP multi-collector transistor, Q4 is an NPN bipolar transistor having a base connected to the base of the multi-collector transistor Q3, a collector connected to the output terminal Y, and an emitter connected to the negative electrode of the DC voltage source Vr. IN1 is a comparator COM1. An inverter having an input terminal connected to the output terminal and an output terminal, F1 is an input terminal D for inputting the output of the inverter IN1, and a comparator COM1
Has an input terminal R connected to its output terminal and an input terminal T for inputting the clock CK1. When the input terminal R goes to a high level, the initial state is entered, and when the input terminal R is at a low level, the clock CK1 input to the input terminal T is input. Flip-flop circuit that latches the value of the input terminal D and outputs it from the output terminal Q at the rising edge of, F2 is an input terminal D connected to the output terminal Q of the flip-flop circuit F1, an input terminal T that inputs the clock CK1, and a comparator A flip-flop circuit having an input terminal R connected to the output terminal of COM1 and having the same function as the flip-flop circuit F1, F3 is a comparator COM
A flip-flop circuit having the same function as the flip-flop circuit F1 having an input terminal R connected to the output terminal of No. 1, an input terminal D connected to the output terminal Q of the flip-flop circuit F2, and an input terminal T for inputting the clock CK1. , IN
2 is an inverter having an input terminal connected to the output terminal Q of the flip-flop circuit F3 and an output terminal; Q5 is connected to the output terminal of the inverter IN2, the base connected to the constant current source I4, and the negative electrode of the DC voltage source Vr. It is an NPN bipolar transistor having an emitter and a collector connected to an output terminal Y.

Next, the operation of the circuit for protecting the semiconductor integrated circuit shown in FIG. 3 from overheating will be described. In the temperature monitor circuit 1, the internal reference voltage Vr is generated by the DC voltage source Vr.
Is set. Since the reference voltage Vr is applied to the base of the transistor Q1 via the resistor r1, when the base-emitter voltage V _BE of the transistor Q1 drops with temperature and drops below the voltage Vr, the transistor Q1 starts operating. To do.

When the transistor Q1 starts operating, the monitor result output circuit 2 starts operating. The transistor Q1 of the temperature monitor circuit 1 has both a temperature monitor and a function of generating an output of the monitor result. When the temperature rises and the transistor Q1 turns on, the base current of the transistor Q2 decreases and the transistor Q1
2 is turned off, the current I2 flowing into the collector of the transistor Q2 is the capacitor C of the discrimination circuit 3 in the next stage.
Flow into 1.

In the discrimination circuit 3, when the voltage at one end of the capacitor C1 exceeds the voltage at one end of the resistor R3, the comparator C
The output of OM1 goes high. As described above, the determination circuit 3 uses the charging time of the capacitor C1 to create the time delay t _d , and transmits the signal to the next stage only when the temperature rises for this time or longer. Time delay t _d
Is calculated by the equation 1. In Equation 1, C1 indicates the capacitance value of the capacitor C1, I2 indicates the current value of the constant current source I2, R2 and R3 indicate the resistance values of R2 and R3, and Vs indicates the output voltage of the power supply Vs.

[0031]

[Equation 1]

When the output of the comparator COM1 becomes low level, the emitter voltage of the transistor Q3 of the signal generating circuit 4 becomes higher than the base voltage, and a current flows from the emitter to the base, and at the same time, the collector voltage becomes the transistor. Feedback to the base of Q1. The feedback path from transistor Q3 to transistor Q1 is
This is for stabilizing the operation of the transistor Q1. The current flowing from the constant current source I3 to the emitter of the transistor Q3 flows to the base of the transistor Q4 and turns on the transistor Q4. When the transistor Q4 is turned on, the output Y becomes low level and a predetermined part of the IC does not operate. The predetermined portion of the IC that is stopped to protect the IC from overheating is preferably a portion that consumes a large amount of power, and for example, a power supply section in which power transistors and the like are often used.

In the counter composed of the flip-flop circuits F1 to F3, all the flip-flop circuits F1 to F3 are reset when the output of the comparator COM1 becomes high level. Therefore, the flip-flop circuit F
The output Q of 3 is at a low level, and the base voltage of the transistor Q5 is at a low level, so that the transistor Q5 is kept off.

Next, when the temperature of the IC is lowered to a temperature at which the overheat protection can be released, the transistor Q1 is turned off, and therefore the transistor Q2 is turned on. At this time, since the current of the constant current source I1 entirely flows into the base of the transistor Q2, the current capacity that the transistor Q2 pulls out is sufficiently larger than the current supplied by the constant current source I2. The voltage sharply decreases and the voltage at one end of the capacitor C1 becomes lower than the voltage at one end of the resistor R3 in a time period sufficiently smaller than the time period during which the capacitor C1 is charged by the constant current source I2.

When the output of the comparator COM1 becomes low level, the transistor Q3 turns off and at the same time the transistor Q4 turns off. At this time, at the same time, the input terminal R of the flip-flop circuits F1 to F3 becomes low level, but the output Q of the flip-flop circuit F3 maintains low level. Therefore, the output of the inverter IN2 becomes high level, and the current from the constant current source I4 changes to the transistor Q.
5 and the transistor Q5 is turned on to set the output Y to the low level to limit the operation of the IC.

Further, when the time of three cycles of the clock CK1 advances, the output Q of the flip-flop circuit F3 changes to the low level, so that the output of the inverter IN2 becomes the low level and the transistor Q5 is turned off to output the output Y. Will be high impedance, so the IC overheat protection will be released.

As described above, the signal generation circuit 4 is internally provided with the delay circuit in order to continue the overheat protection operation for a certain time even if the temperature is lowered and the overheat protection is released. Then, the flip-flop circuit F forming the counter
1 to F3 work so that the output terminal maintains the overheat protection operation state by keeping Q5 in the ON state for a certain time even if the signal from the determination circuit 3 becomes low level and is cooled to a temperature at which the overheat protection operation starts. In this way, the operation is started in the overheat condition for a certain time or longer, and the output is fixed for a certain time after the overheat protection operation is released.Therefore, a malfunction occurs in the temperature hysteresis loop and the output is locked. It is possible to obtain an accurate overheat protection circuit that does not have such a problem.

The number of flip-flop circuits in the counter may be increased or decreased according to the clock frequency or the setting of the duration of the overheat protection operation, and the number is not limited to three, and may be increased or decreased.

<Embodiment 2> Next, a circuit for protecting an IC according to a second embodiment of the present invention from overheating will be described.
FIG. 4 is a block diagram showing the structure of a circuit for protecting an IC from overheating according to the second embodiment of the present invention. 4, blocks denoted by reference numerals 1 to 3 are the same as the temperature monitor circuit 1, the monitor result output circuit 2 and the determination circuit 3 of the circuit for protecting the IC according to the first embodiment shown in FIG. 1 from overheating. Blocks having a function, 4a is a signal generation circuit that outputs the output c of the determination circuit 3 by extending it for a predetermined period, and 5 is connected to the outside of the signal generation circuit 4a and the signal generation circuit 4a extends by the capacity thereof. Is a capacitor for adjusting the length of the period.

In the signal generating circuit 4a of FIG. 4, the capacitor 5 for determining the time is externally attached, and the time for keeping the overheat protection state after the IC becomes lower than the reference temperature is made variable by setting the capacity of the capacitor 5. Is. In the IC in which the temperature monitor circuit 1 is installed, the way in which the temperature drops depends on the difference in heat capacity and heat dissipation efficiency. Therefore, when the temperature drop per unit time is large, the capacity of the capacitor 5 is set so that the time for maintaining the overheat protection state is lengthened.

FIG. 5 is a circuit diagram showing an example of the overheat protection circuit shown in FIG. From the temperature monitor circuit 1 to the discrimination circuit 3
Up to the above, the configuration is the same as that of the overheat protection circuit of the first embodiment shown in FIG. NAND in the signal generation circuit 4a timer part
A multivibrator using two gates is arranged to set the extension time.

In the signal generating circuit 4a, I3 and I4 are constant current sources for supplying a direct current kept at a predetermined value from the power supply potential Vcc, and Q3 is connected to the output terminal of the comparator COM1 and the constant current source I3. P having an emitter and one collector connected to the base of the NPN bipolar transistor Q1, and another collector and base connected to each other
NP multi-collector transistor, Q4 is an NPN bipolar transistor having a collector connected to the base of the multi-collector transistor Q3 and having a base connected to the output terminal Y, and an emitter connected to the negative electrode of the DC voltage source Vr. ND1 is a comparator COM1. A 2-input NAND gate having one input terminal connected to the output terminal and the other input terminal and an output terminal, C2 is a 2-input NAND gate ND1
, A capacitor having one end and the other end connected to the output terminal, R4 is a resistor having one end and the other end connected to the power supply potential Vcc, R5 is one end connected to the other end of the capacitor C2 and a DC voltage source A resistor having the other end connected to the negative electrode of Vr, ND2 is one input terminal connected to the other end of the capacitor C2, the other input terminal connected to the other end of the resistor R4, and the other input terminal of the NAND gate ND1. A two-input NAND gate having an output terminal connected to
IN3 is an inverter having an input terminal connected to the output terminal of the NAND gate ND2 and an output terminal, Q5 is an output terminal of the inverter IN3 and a base connected to the constant current source I4, and an emitter connected to the negative electrode of the DC voltage source Vr. It is an NPN bipolar transistor having a collector connected to the output terminal Y.

Next, the operation of the circuit shown in FIG. 5 for protecting the IC from overheating will be described. The operation of the transistors Q3 and Q4 is the same as the circuit for protecting the IC from overheating shown in FIG.

When the temperature of the IC becomes higher than the reference temperature requiring overheat protection, the output of the comparator COM1 becomes high level, and therefore the inputs of the NAND gate ND1 both become high level. The voltage at one end becomes even lower than the voltage level of the negative electrode of the constant voltage source Vr. After a while, the voltage at one end of the resistor R5 is changed to the constant voltage power source V by the charge supplied through the resistor R5.
Return to r. At this time, one of the input terminals of the NAND gate ND2 is at low level and the other is at high level.
The output of the NAND gate ND2 maintains high level.

Next, as a result of the overheat protection, when the temperature of the IC falls to the reference temperature, the output of the comparator COM1 becomes low level. Since one of the input terminals of the NAND gate ND1 becomes low level, the output of the NAND gate ND1 changes from high level to low level. By this change,
The voltage at one end of the resistor R5 momentarily reaches a high level,
The output of the NAND gate ND2 changes from high level to low level. Therefore, the output of the inverter IN3 becomes high level, the transistor Q5 is turned on, and the output signal is output from the output terminal Y to regulate the operation of the IC.

When the charge of the capacitor C2 is extracted through the resistor R5 after a short time, the NAND gate N
Since one of the inputs of D2 becomes low level, the output of the NAND gate ND2 changes to high level and the transistor Q5 turns off, so that the overheat protection state is released.

The time for which the signal generation circuit 4a extends the overheat protection state of the IC is proportional to the capacity of the capacitor C2.
By adjusting the externally attached capacitor C2, the time until the overheat protection operation is released can be adjusted.

<Third Embodiment> FIG. 6 shows a block diagram of a circuit for protecting a semiconductor integrated circuit from overheating according to a third embodiment. In FIG. 6, blocks indicated by reference numerals 1 to 3 are
A block having the same function as the temperature monitor circuit 1, the monitor result output circuit 2 and the discrimination circuit 3 of the circuit for protecting the IC according to the first embodiment shown in FIG. 1 from the overheat, and 4b is an output c of the discrimination circuit 3. Is extended for a predetermined period and is output, and 6 is a capacitor that is connected to the outside of the signal generation circuit 4b and that adjusts the length of the predetermined period that the signal generation circuit 4b extends by the capacitance thereof.

FIG. 7 is a circuit diagram showing the structure of a circuit for protecting the semiconductor integrated circuit according to the third embodiment from overheating. Figure 7
In the above, C3 is a capacitor having one end connected to the output terminal of the NAND gate ND1 and the other end connected to one end of the resistor R5. As can be seen by comparing FIGS. 7 and 5, the overheat protection circuit according to the third embodiment and the overheat protection circuit according to the second embodiment have the same circuit configuration. The overheat protection circuit shown in FIG. 6 is different from the overheat protection circuit of the second embodiment shown in FIG. 4 in that a signal is sent to a capacitor 5 for varying a predetermined time of a signal generation circuit 4a in the second embodiment. The point is that the capacitor 6 built in the generation circuit 4b is used.

Although the capacity of the capacitor 6 can be set in accordance with the difference in the cooling rate of the semiconductor integrated circuit due to the difference in the degree of integration of the semiconductor integrated circuit and the heat radiation effect, after the setting, the time until the overheat protection operation is released is fixed. It But capacitor 6
The external elements are reduced by incorporating.
Of course, the same effects as those of the first and second embodiments can be expected in the operation of the entire circuit.

<Fourth Embodiment> FIG. 8 is a circuit diagram showing a structure of a circuit for protecting a semiconductor integrated circuit according to a fourth embodiment of the present invention from overheating. In FIG. 8, 1a is a temperature monitor circuit provided in the semiconductor integrated circuit for detecting whether or not the temperature of the semiconductor integrated circuit is higher than a predetermined temperature, and 2a is a signal according to the monitoring result of the temperature monitor circuit 1. It is a monitor result output circuit for outputting, and the other blocks indicated by reference numerals 3 and 4 are portions corresponding to the discrimination circuit 3 and the signal generation circuit 4 shown in FIG.

In the temperature monitor circuit 1a, I5, I6
Is a constant current source for supplying a direct current maintained at a predetermined value from the power supply potential Vcc, R6 is a resistor having one end and the other end connected to the ground potential point GND, and Q6 is a resistor R6
Is an NPN bipolar transistor having a base connected to the other end of the resistor, an emitter connected to one end of the resistor R6, and a collector connected to the constant current source I5. A voltage is supplied to both ends of the resistor R6 from a DC voltage power supply.

In the monitor result output circuit 2a, Vr1
Has a negative electrode connected to the ground potential GND and a positive electrode I
A DC voltage power source that generates a predetermined DC voltage between the positive and negative electrodes regardless of the temperature change of C, R7 is a resistor having one end connected to the other end of the resistor R6 and the other end, and R8 is the other end of the resistor R7. A resistor having one end connected to and the other end connected to the positive electrode of the DC voltage power supply Vr1, Q7 is a base connected to the collector of the transistor Q6, a collector connected to the constant current source I6, and an emitter connected to the ground potential GND. And an NPN bipolar transistor that outputs a detection result from the collector to the determination circuit 3, and R9 is a ground potential GN.
A resistor having one end and the other end connected to D, Q8 is the other end of the resistor R9, a base connected to the signal generating circuit 4, an emitter connected to one end of the resistor R6, and a collector connected to the constant current source I5. An NPN bipolar transistor having a transistor Q9, a PN having an emitter connected to the positive electrode of the DC voltage power supply Vr1, a collector connected to one end of the resistor R8, and a base connected to the collector of the transistor Q8.
P bipolar transistor, R10 is transistor Q9
It is a resistor connected between the base and emitter of. The voltage fed back from the signal generation circuit 4 to the base of the transistor Q8 is a voltage for stabilizing the operation of the temperature monitor circuit 1 and the monitor result output circuit 2a.

This is a modification of the temperature monitor circuit 1a and the monitor result output circuit 2a in which the resistance division value of the internal reference voltage V _r1 is compared with the base-emitter voltage V _{BE of the} transistor. By doing so, the reference DC voltage source can be made one.

The discrimination circuit 3 and the signal generation circuit 4 may be combined with any of the circuits of the above embodiments.

<Fifth Embodiment> FIG. 9 is a circuit diagram showing a structure of a circuit for protecting a semiconductor integrated circuit according to a fifth embodiment of the present invention from overheating. In FIG. 9, 1b is a temperature monitor circuit provided in the semiconductor integrated circuit for detecting whether or not the temperature of the semiconductor integrated circuit is higher than a predetermined temperature, and 2b is a signal according to the monitoring result of the temperature monitor circuit 1. The temperature monitor circuit 1b is provided in the bandgap constant voltage circuit Ci1, and the other blocks indicated by reference numerals 3 and 4 are the determination circuit 3 and the signal generation circuit 4 shown in FIG. Is a part corresponding to.

In the bandgap constant voltage circuit Ci1, R11 has a resistor having one end and the other end connected to the power supply potential Vcc, and Q10 has an emitter and a collector and a base connected to the other end of the resistor R11. An NPN bipolar transistor that exhibits a diode function between bases, Q11 has a collector connected to the power supply potential Vcc and a base and emitter connected to the emitter of the transistor Q10, and is fixed from the power supply potential Vcc to a node to which the emitter is connected. NPN bipolar transistor for supplying current, Q12 is emitter and transistor Q1
NPN that has a collector and a base connected to the emitter of 0 and exhibits a diode function between the collector and the base
A bipolar transistor, Q13 is a base, an emitter connected to the emitter of the transistor Q12, and a ground potential GN.
A PNP bipolar transistor having a collector connected to D, a constant voltage being applied to the base, and a constant current flowing between the emitter and the collector. The above portion of the band gap type constant voltage circuit Ci1 is a constant current circuit unit that supplies a constant current through the transistor Q11.

Further, the band gap type constant voltage circuit Ci1
In, Q14 is a PNP bipolar transistor which has an emitter and a collector and a base connected to the emitter of the transistor Q11 and exhibits a diode function between the collector and the base. Q15 is an emitter connected to the emitter of the transistor Q11 and a base of the transistor Q14. And a transistor Q14 having a base connected to the collector and a collector connected to the base of the transistor Q13.
, A PNP bipolar transistor for flowing a current proportional to the current flowing through the transistor, Q16 is an NPN bipolar transistor for determining the current flowing through the transistor Q14 having a base, a collector connected to the collector of the transistor Q14 and an emitter connected to the ground potential GND. , R13 has a resistor having one end and the other end connected to the emitter of the transistor Q11, Q19 has one end of the resistor R13 and a collector and base connected to the base of the transistor Q16, and an emitter connected to the ground potential GND. An NPN bipolar transistor for determining the current flowing through the transistor Q16, R12 is provided at one end and the transistor Q1.
A resistor having an opposite end connected to 1, a Q18 is an NPN bipolar transistor having an emitter and a collector connected to one end of a resistor R12, and a base connected to the base of a transistor Q19, and R14 is connected to an emitter of the transistor Q18. A resistor having an end and the other end connected to the ground potential GND, Q17 is an NPN bipolar transistor having a collector connected to the collector of the transistor Q15, an emitter connected to the ground potential GND, and a base connected to the collector of the transistor Q18, C4.
Is a capacitor having one end connected to the base of the transistor Q13 and the other end connected to the collector of the transistor Q18.

The base-emitter voltage of the transistor Q17 is V _BE17 , the difference between the base-emitter voltage of the transistor Q19 and the base-emitter voltage of the transistor Q18 is ΔV _BE, and the resistance values of the resistors R12 and R14 are r12. , R14 and the voltage generated between the collector and emitter of the transistor Q17 is E _REF , E _REF =
It is given by V _BE17 + ΔV _BE × r12 / r14. Since the amplified voltage ΔV _BE × r12 / r14 which is inverted and amplified is [Delta] V _BE opposite polarity, if the resistance value r12, r14 suitably choose, temperature changes cancel each other between the V _BE17 and ΔV _BE × r12 / r14 can do.

However, since the base-emitter voltage V _{BE17 of} the transistor Q17 changes depending on the temperature of the IC, by comparing it with the reference voltage, it is determined whether the temperature of the IC has reached a temperature at which overheat protection should be performed. Can be detected.

In the monitor result output circuit 2b, I7,
I8 is a constant current source for supplying a direct current maintained at a predetermined value from the power supply potential Vcc, and R15 is a transistor Q.
A resistor having one end connected to the emitter of 11 and the other end, R16 is a resistor having one end connected to the other end of the resistor R15 and the other end connected to the ground potential GND, and the transistor Q20 is a constant current source I7. A PNP bipolar transistor having a connected emitter and a base connected to the base of a transistor Q17 and a collector; Q21 a PNP bipolar transistor having an emitter connected to the constant current source I7 and a base and collector connected to one end of a resistor R15; Q22 is an NPN bipolar transistor having a collector and a base connected to the collector of the transistor Q20 and an emitter connected to the ground potential GND, and Q23 is a collector connected to the collector of the transistor Q21 and a base connected to the base of the transistor Q22. And ground potential NPN bipolar transistor having an emitter connected to ND, the transistor Q23
Is an NPN bipolar transistor having a base connected to the collector, an emitter connected to the ground potential GND, and a collector connected to the constant current source I8 and the discrimination circuit 3.

The voltage generated at one end of the resistor R16 and applied to the base of the transistor Q21 is the reference voltage corresponding to the reference temperature at which overheat protection is started. A constant current is supplied to the resistor R16 from the transistor Q11. In order to stabilize the operation of the circuit, the transistor Q21
A predetermined voltage is fed back to the base of the signal generation circuit 4 in accordance with the output.

The temperature monitor circuit 1b and the monitor result output circuit 2b shown here are composed of a combination circuit of a band gap type constant voltage circuit and a comparator.
In this embodiment as well, the discrimination circuit 3 and the signal generation circuit 4 may be combined with any of the circuits of the previous embodiments.

[0064]

As described above, according to the circuit for protecting the semiconductor integrated circuit of the invention described in claim 1 from overheating, the output of the temperature detecting means is lost only for the output of the temperature detecting means continuously given for a predetermined time. Since it is configured to include a signal output means for extending the output of the temperature detecting means for a predetermined period even after the output, the operation is started in the overheated state for a predetermined time or longer, and the overheat protection operation is released. Since the output can be fixed for a predetermined period after the start, it is possible to obtain an overheat protection circuit that does not have a temperature hysteresis loop and does not malfunction due to malfunction in the temperature hysteresis loop and lock the output. effective.

According to the second aspect of the circuit for protecting the semiconductor integrated circuit from overheating, when the output from the temperature detecting means is not given for a predetermined time, the determining means determines the output of the temperature detecting means. I don't have to respond
After the temperature of the semiconductor integrated circuit drops below a specified temperature,
With the signal generation means, it is possible to continue to output a signal for a predetermined period of time, and it is possible to easily configure an overheat protection circuit that does not malfunction in the temperature hysteresis loop and lock the output. is there.

According to the circuit for protecting the semiconductor integrated circuit from overheating of the third aspect of the invention, a predetermined period is set according to the cooling rate of the semiconductor integrated circuit, and the overheat protection corresponding to each semiconductor integrated circuit is provided. The effect is that it can be easily performed.

According to the fourth aspect of the present invention, in the circuit for protecting the semiconductor integrated circuit from overheating, the length of the predetermined period can be adjusted according to the capacity built in the semiconductor integrated circuit. The effect is to easily obtain a circuit that protects the possible small size from overheating.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a circuit for protecting a semiconductor integrated circuit from overheating according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing an operation of the overheat protection circuit shown in FIG.

FIG. 3 is a circuit diagram showing a configuration of a circuit for protecting the semiconductor integrated circuit from overheating according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a circuit for protecting a semiconductor integrated circuit from overheating according to a second embodiment of the present invention.

5 is a circuit diagram showing an example of a configuration of a circuit for protecting the semiconductor integrated circuit shown in FIG. 4 from overheating.

FIG. 6 is a block diagram showing a configuration of a circuit for protecting a semiconductor integrated circuit from overheating according to a third embodiment of the present invention.

7 is a circuit diagram showing an example of the configuration of a circuit for protecting the semiconductor integrated circuit shown in FIG. 6 from overheating.

FIG. 8 is a circuit diagram of a circuit for protecting a semiconductor integrated circuit from overheating according to a fourth embodiment of the present invention.

FIG. 9 is a circuit diagram of a circuit for protecting a semiconductor integrated circuit from overheating according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a circuit for protecting a conventional semiconductor integrated circuit from overheating.

FIG. 11 is a characteristic diagram for explaining the operation of a conventional circuit that protects a semiconductor integrated circuit from overheating.

[Explanation of symbols]

1, 1a, 1b temperature monitor circuit, 2, 2a, 2b monitor result output circuit, 3 determination circuit, 4, 4a, 4b signal generation circuit.

[Procedure amendment]

[Submission date] May 16, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 11

[Correction method] Change

[Correction content]

FIG. 11

Claims (4)

[Claims] 1. A temperature detecting means which is provided at a predetermined position of a semiconductor integrated circuit and detects whether or not the temperature at the predetermined position of the semiconductor integrated circuit exceeds a predetermined reference temperature and outputs a detection result. And a signal output means for extending the output of the temperature detecting means for a predetermined period even after the output of the temperature detecting means is exhausted, as long as the output of the temperature detecting means is continuously given for a predetermined time, A circuit that protects semiconductor integrated circuits from overheating. 2. The signal output means determines whether or not the output of the temperature detecting means is continuously applied for a predetermined time, and the temperature detecting means of the temperature detecting means according to the determination result of the determining means. 2. The semiconductor integrated circuit according to claim 1, further comprising a signal generation unit that generates and outputs a signal during a period in which the output continues after the determination by the determination unit and during the predetermined period after the output ends. Circuit that protects from overheating. 3. The semiconductor integrated circuit according to claim 2, wherein the signal generating means is capable of adjusting the length of the predetermined period according to a capacitance connected to the outside of the semiconductor integrated circuit. Circuit that protects against overheating. 4. The semiconductor integrated circuit according to claim 2, wherein the signal generating means is capable of adjusting the length of the predetermined period according to the capacity built in the semiconductor integrated circuit. Circuit to protect from.